My teacher and mentor Vaidya Rama Kant Mishra came from a 5,000 year old lineage of Ayurveda whose specialty was Dermatology. They originally came from the island of Madagascar and were known for their “worship” of the sun since it gave life to us and contributed to our emotional and physical well-being and health.
I remember Vaidya told me one day that the sunlight hitting the skin did more than just manufacture Vitamin D, but we hadn’t yet discovered most of the things it could do.
Remembering his words, I always made it a point to try to follow up on any research that might reveal more information about the sunlight’s amazing health benefits than just its role in producing Vitamin D through the various layers of the skin.
Following is a lot of the information I have gathered through the years on the role the sunlight plays in giving us good mental, emotional and physical health. I’m sure research will produce even more benefits in future years. So here is what we know so far:
The human skin is the largest organ, accounting for around 12% to 15% of a person’s total weight. The skin has several layers that help protect the muscles, ligaments, internal organs and bones from outside threats.
The epidermis is the visible layer of the skin — it is waterproof and prevents infections.The invisible portion of the sun’s radiation is called ultraviolet radiation, also known as UV light. UV light is available year-round in the tropics and during part of the year farther north and south. There are three main varieties of ultraviolet light: UVA, UVB and UVC.
UVA does not stimulate Vitamin D production, but it does stimulate the production of nitric oxide, which is vital for human health.
UVB stimulates the epidermis to produce Vitamin D.
UVC radiation is the highest energy portion of the UV radiation spectrum. UVC radiation from the sun does not reach the earth’s surface because it is filtered by the earth’s outer atmosphere and the ozone layer.
All tissues in the body have Vitamin D receptors, and the brain and central nervous system must have Vitamin D to function properly. Sun exposure is the direct, natural way to obtain significant amounts of Vitamin D.
Exposure to the sun provides 90% of the Vitamin D for humans. Vitamin D from sunlight can be synthesized in the skin mostly around midday, from 10 am to 2 pm. The more skin that is exposed the greater the amount of Vitamin D is produced. A good rule of thumb is that the shadow of an object should be shorter than its height — this is the best type of sunlight for you to produce Vitamin D, again, around 10 am to 2 pm. As much as 20,000 IU of Vitamin D can be produced with whole body exposure at midday.
Vitamin D produced in the skin from sunlight exposure does not lead to Vitamin D toxicity and is considered safe, as the body limits its own production This is not true for Vitamin D supplementation which you can overdose on if you take too much orally.
In the North American winter, due to the low angle of the sun, Vitamin D cannot be produced through UVB sun exposure north of 35 degree latitude. The reason is that UVB rays are at an angle and are filtered out through the atmosphere. This is the same for the Southern winter, south of 35 degree latitude. But don’t think that just because Vitamin D cannot be synthesized by the skin during winters, or during early morning or late afternoon, one should not try to obtain sunlight during these periods. The sun has numerous other benefits at all times of the day and at all seasons and you should take advantage of it whenever it is available.
The time required to make sufficient Vitamin D varies according to a number of environmental, physical and personal factors, but is typically short and less than the amount of time needed for skin to redden and burn. Full body UV exposure or the equivalent of being slightly pink 24 hours after exposure will provide between 10,000 and 25,000 IU of Vitamin D. The surface area of the skin exposed will influence the amount of Vitamin D made after UVB sun exposure, and lying down exposes more skin than standing up. A key to being safe is to leave the sun at the first sign of pinkness. Tanning acclimates the skin to reduce the risk of overexposure, but the inability to tan is a risk factor for skin cancer.
I think that most people aren’t aware of the fact that the skin makes more than just Vitamin D from sun exposure: it makes nitric oxide, dopamine, serotonin, endorphins and BDNF (a neuron growth factor and preventer of nerve death), and photoproducts that may reduce the risk of MS, heart disease and cancer, as well as many other diseases.
Morning sunlight improves sleep. Your body creates a hormone called melatonin which helps you sleep. Sunshine regulates your circadian rhythm by telling your body when to increase and decrease your melatonin levels. So, the more daylight exposure you can get, the better your body will produce melatonin when it’s time to go to sleep. Any parent will tell you how well their children sleep at night after playing outside all day in the sunshine.
In fact, studies show that a lack of daylight disrupts some hormonal processes in our bodies causing our circadian rhythms to shift which might cause some people go to sleep later and later in the evenings resulting in an increased risk of depression. Many of the teenagers I see who suffer from depression go to bed very late, past the bedtime recommended by the ancient Ayurvedic doctors, which is 10:00 PM.
The earliest morning sun is responsible for resetting the circadian rhythm. Try to be outside for a half hour when the sun rises each morning. A 2019 study found that exposure to morning sunlight results in greater alertness. A 2017 study published in the journal Sleep Health demonstrated how people who are exposed to sunlight in the morning sleep better at night and feel less stressed and depressed than people who don’t get access to morning sunlight. Research from Denmark has shown that morning light relieves anxiety by reducing the activity of the brain’s fear center.
The ancient doctors predicted this as well stating that we should wake up at the crack of dawn and if in fact we woke up once the sun was already up, known as the kapha time of day, we would have a dense heavy feeling of lethargy and depression would last the rest of the day. The kapha time of day is from 6 am to 10 am, so we should always wake up no later than 6 am if at all possible in order to feel the most energetic during the day.
Waking up early and exposing yourself to morning light is one way to lock the body into a good 24 hour schedule which means better sleep at night and more alert, energetic mornings. When those rhythms are off, you might have trouble getting out of bed in the morning and then have trouble falling asleep at night.
Our brains produce a protein called BDNF which promotes growth of neurons and prevents nerve cell death. Researchers have shown that BDNF has an effect on behavior, mood (depression), brain adaptation (plasticity). BDNF levels increase in spring and summer and decrease in fall and winter. BDNF levels increase significantly after bright light exposure. Research has shown that bright sunlight increases new nerve cell growth in the adult rat brain. To quote from the study: “We are actually seeing new brain cells being built by bright sunlight exposure combined with exercise.”
How does sunlight help depression? Well, for one thing, the sunshine boosts your body’s production of serotonin, which is a neurotransmitter that improves your mood and helps you stay calm and focused.This neurotransmitter serotonin is a natural “upper,” working in synchronization with the natural “downer,” melatonin. When we wake up to sunshine the light enters the eye and stimulates serotonin production. We then quickly become awake and invigorated and melatonin is suppressed. At the end of the day, however, the bright light disappears, melatonin levels rise and serotonin levels diminish. We begin to feel sleepy and ideally retire for a good night’s rest.
Sunlight dramatically increases serotonin levels in the brain. Researchers in Australia measured serotonin levels in response to varying degrees of bright light. They withdrew blood samples from 101 men during varying weather conditions and seasons. The results were remarkable: Men who were measured on a very bright day produced eight times more serotonin than those who were measured on a cloudy, dismal day.
Selective serotonin reuptake inhibitors (SSRI) such as Prozac work by keeping serotonin in circulation since lack of serotonin may cause depression. Sun exposure can increase the amount of serotonin in the circulation by 800% in one day, without the toxic side effects of the SSRI’s.
They also observed that the effect of bright light was immediate and that there was no holdover from day to day. Serotonin levels were also seven times higher in summer than winter. This is why people develop seasonal affective disorder (SAD), a form of mood disorder occurring especially in winter, and characterized by depression, irritability, aggression, weight gain, fatigue and inability to concentrate.
It has also been shown that depressed psychiatric patients residing in sunny rooms stayed in the hospital 2.6 fewer days on average than those who had darker rooms. The sunny rooms had windows, so it is likely that endorphins created by the sun’s rays entering through the windows were responsible for making the patient feel better. It could not have been from Vitamin D as was previously thought because the UVB light necessary to produce Vitamin D is filtered out by window glass.
Another study showed that the more TV teenagers watch, the more likely they are to be depressed as adults. For each hour of TV watched, the rate of depression increased significantly. Sitting in dark rooms with TV on with less sunlight create insufficient levels of Vitamin D, endorphins, and serotonin, leading to long-term mood disorders. Add to this a sedentary lifestyle, and junk food causing obesity creating a perfect recipe for depression.
The brain also produces endorphins by the skin in response to sun exposure. Endorphins elevate the mood while producing a sense of well being.
Dopamine is a neurotransmitter that is responsible for making us feel bliss, euphoria and gives us enhanced motivation and satisfaction.This “upper” as it is sometimes called, also increases with exposure to sunlight.
So serotonin, endorphins and dopamine, famously known as the “happy hormones” which promote feelings like pleasure, happiness and even love are all produced from exposure to sunlight.
Nitric oxide (NO) is produced by the skin after exposure to the UVA from preformed stores of NO in the skin. NO reduces blood pressure since it is a potent vasodilator, which means it opens up the blood vessels, and when released into the arteries by UVA stimulation, it causes increased blood flow in the blood vessels, which lowers blood pressure. It gets produced even if filtered through window glass (unlike Vitamin D which needs direct sunshine on the skin to be made).
Seasonal cold and flu outbreaks are related to lower solar UVB doses. In the northern hemisphere, influenza occurs in December through March. In the southern hemisphere, outbreaks occur June through September- almost exclusively in winter in both hemispheres. The outbreaks in each case occur in times of lowest sun exposure.
Relatively new and very important research shows that sunlight boosts the effectiveness of T-cells. T cells are a huge part of the immune system, they are a type of lymphocyte which recognizes and binds to foreign invaders, rendering them harmless.
The UV spectrum of sunlight stimulates the production of hydrogen peroxide which causes the T-cells to move to the site of infection to kill noxious bacteria. T cells, whether they are helpers or killers need to move to get to the site of infection to do their work. This study shows how sunlight directly activates these key immune cells by increasing their movement.
It turns out that the skin has a large share of the total T-cells in humans, about twice the number circulating in the blood. So the sun exposure activates the T-cells to move quickly to areas of the body where they are needed to fight infection. This is why there is less influenza, pneumonia, colds and flus in the winter.
Vitamin D has a direct influence on MS patients. MS is found in the northern part of the northern hemisphere and is virtually non-existent in sunny countries around the equator. The risk of MS in far northern areas is more than 100 times greater than it is in areas around the equator, where sunlight is intense, and the rate of MS approaches zero.
A sudden worsening of MS symptoms is known as a relapse or exacerbation and research shows that these events are profoundly related to serum Vitamin D levels. One study shows a correlation between Vitamin D levels and the rate of relapse in that for every increase in serum Vitamin D levels of 10 units, there is a 34% decrease in the risk of relapse in young people.
Remember, 90% of serum Vitamin D is derived from sun exposure and the sun has even more protective effects on MS beyond Vitamin D. One study concluded that Vitamin D supplementation alone may not replace the ability of the sun’s UV rays to reduce MS susceptibility. What they found is that UV light inhibits spinal cord inflammation and demyelination by inhibiting a chemical known as a cytokine. Inflammatory cytokines are the cause of inflammation and autoimmune attacks resulting in MS.
And another study proved that sun exposure independent of Vitamin D has a direct effect on neurodegeneration where they found that greater summer sun exposure predicted greater grey matter volume and whole brain volume. It was also found that exposure to UV radiation help prevent the body from attacking itself by increasing the T and B cells which modulate and suppress the immune system. MS is an autoimmune disease in which the immune system attacks and destroys the myelin sheath of the body’s own nervous system. The myelin sheath is the protective covering to the nerve cells. The regulatory or T suppressor cells suppress these attacks preventing the disease. And the B regulatory cells are also a part of the immune system and can through their suppressive functions decrease inflammation through the production of anti-inflammatory cytokines.
This research is important because it shows how sun exposure works against MS in several different ways, only one of which may be the stimulation of Vitamin D production.
The UVB light found in sunlight suppresses inflammation in the skin and thus has been used to successfully treat skin diseases such as psoriasis and eczema. Many patients report to me that their skin conditions clear up in the summer months with more exposure to the sun.
So, as you can see, the sunlight is extremely important for our health. That’s why, after the end of the long, cold winter most of us can hardly wait to feel the sun on our skin again and we breathe a sigh of relief as we feel the sun’s rays penetrating every fiber of our being, causing an immediate increase in our mood and at the same time helping your entire body to heal from the inside out.
I hope you found this information useful as you strive to live a healthy life.